Talks with potential contractors for a £185m project connected to the M4 relief road are to be held by the Welsh Government.
Ministers have not decided whether to build the road, but they want to hold an event for firms interested in works to improve Newport docks, needed so the project can go ahead.
The government said officials were having "non-committal discussions".
The move sparked concern from a campaigner opposed to the M4 project.
First Minister Mark Drakeford told the South Wales Argus newspaper that an announcement on the road is due within the first two weeks of the next assembly term, which begins 29 April.
A page on the Sell2Wales website said Welsh ministers "wish to hold an industry day to introduce the project to the market and also to assess market conditions for tendering for the works in order to inform their strategic decision-making on the packaging of the project".
Asked why this was happening when no decision on the M4 relief road had been made, a spokeswoman told BBC Wales that officials were "engaging in early, non-committal, discussions with potential contractors".
This was "to enable minor preparatory steps to be taken so that lengthy procurement processes could proceed efficiently in the event that the statutory orders are made", she added.
The owner of the docks, Associated British Ports, had objected to the M4 Relief Road proposal to build a 14 mile (23km) motorway to the south of the city, saying the bridge over the River Usk would have cut across the site.
The work includes new buildings for firms operating in the port, and developing the south dock to overcome concerns the bridge would cut off access to the north dock for some vessels.
At the time ABP said the agreement allowed them to relocate services that would have been "severely impacted" if the preferred route went ahead.
It was thought that the project would cost £136m but the website lists a value of £185m.
"The cost estimate is consistent with the information at public inquiry which set out the £136m of works necessary to relocate tenants within Newport Docks and accommodate the M4 project," the Welsh Government spokeswoman said.
"The quoted figure includes £17.5m of existing project risk allowance, which was allocated for bridge protection measures and the remainder is risk/contingency allowances that were also scrutinised at the public inquiry."
James Byrne, of Wildlife Trusts Wales, said he was concerned about the news.
He warned a decision to go ahead with the M4 relief road would be "against the advice of Natural Resources Wales and the Future Generations Commissioner".
It would not be in "alignment with the Environment Act and the Wellbeing of Future Generations Act around biodiversity, climate change, and sustainability", he added.